It is known that some metal oxides and metal complexes emit a visible light by receiving irradiation of an ultraviolet. Using this property, the metal oxides and metal complexes are used for an optical material such as a fluorescent body.
The light emission property of the metal oxide and metal complex is thought to be due to the crystal condition and an electron donor type defect in the surface (a hole of interstitial metal and oxygen). It is known that metal oxides in high crystal condition and metal oxides in the surface of which an electron donor type defect is generated emit a visible light by receiving irradiation of an ultraviolet. Also, it is known that metal complexes emit a light when it returns to the ground state from the excited state in which it is excited by receiving irradiation of an ultraviolet.
A thermoplastic resin composition containing a metal oxide is generally produced by kneading metal oxide fine particles and a thermoplastic resin, and is strongly influenced by particle diameter and aggregation state of the metal oxide fine particles. In the case where the particle diameter is large, light emission intensity is reduced or light emission is not provided. In the case where aggregation of fine particles is progressed, light emission intensity is reduced or light emission is not provided. Also, the transparency of the molded body may be compact may become lower.
In order to solve the problem, Patent document 1 proposes a production method of a thermoplastic resin composition in which an appropriate amount of the aluminum-type polymerization catalyst used at the time of polymerization is left. The molded body obtained by this method keeps transparent, and emits a visible light by receiving irradiation of an ultraviolet. However, it is difficult to control the amount of the metal oxide which exists in the molded body, and the light emission intensity is not also high.
Patent document 2 proposes a production method of a thermoplastic resin composition in which a thermoplastic resin and a metal complex is heated. The molded body obtained by this method has ultraviolet absorptivity. This molded body may emit a visible light by receiving irradiation of an ultraviolet, but the light emission intensity is not high.